FOXA2 activates HIF2α expression to promote tumor progression and is regulated by the E3 ubiquitin ligase VHL in renal cell carcinoma.

Renal cell carcinoma (RCC) is a frequent malignancy of the urinary system with high mortality and morbidity. However, the molecular mechanisms underlying RCC progression are still largely unknown. In this study, we identified FOXA2, a pioneer transcription factor, as a driver oncogene for RCC. We show that FOXA2 was commonly upregulated in human RCC samples and promoted RCC proliferation, as evidenced by assays of cell viability, colony formation, migratory and invasive capabilities, and stemness properties. Mechanistically, we found that FOXA2 promoted RCC cell proliferation by transcriptionally activating HIF2α expression in vitro and in vivo. Furthermore, we found that FOXA2 could interact with VHL (von Hippel‒Lindau), which ubiquitinated FOXA2 and controlled its protein stability in RCC cells. We showed that mutation of lysine at position 264 to arginine in FOXA2 could mostly abrogate its ubiquitination, augment its activation effect on HIF2α expression, and promote RCC proliferation in vitro and RCC progression in vivo. Importantly, elevated expression of FOXA2 in patients with RCC positively correlated with the expression of HIF2α and was associated with shorter overall and disease-free survival. Together, these findings reveal a novel role of FOXA2 in RCC development and provide insights into the underlying molecular mechanisms of FOXA2-driven pathological processes in RCC.

Consensus subtypes of hepatocellular carcinoma associated with clinical outcomes and genomic phenotypes.

BACKGROUND AND AIMS: Although many studies revealed transcriptomic subtypes of HCC, concordance of the subtypes are not fully examined. We aim to examine a consensus of transcriptomic subtypes and correlate them with clinical outcomes. APPROACH AND RESULTS: By integrating 16 previously established genomic signatures for HCC subtypes, we identified five clinically and molecularly distinct consensus subtypes. STM (STeM) is characterized by high stem cell features, vascular invasion, and poor prognosis. CIN (Chromosomal INstability) has moderate stem cell features, but high genomic instability and low immune activity. IMH (IMmune High) is characterized by high immune activity. BCM (Beta-Catenin with high Male predominance) is characterized by prominent ß-catenin activation, low miRNA expression, hypomethylation, and high sensitivity to sorafenib. DLP (Differentiated and Low Proliferation) is differentiated with high hepatocyte nuclear factor 4A activity. We also developed and validated a robust predictor of consensus subtype with 100 genes and demonstrated that five subtypes were well conserved in patient-derived xenograft models and cell lines. By analyzing serum proteomic data from the same patients, we further identified potential serum biomarkers that can stratify patients into subtypes. CONCLUSIONS: Five HCC subtypes are correlated with genomic phenotypes and clinical outcomes and highly conserved in preclinical models, providing a framework for selecting the most appropriate models for preclinical studies.

The association between fatty liver index and onset of diabetes: secondary analysis of a population-based cohort study.

BACKGROUND: According to research, the fatty liver index (FLI) is associated with diabetes. However, few studies have been conducted to investigate the relationship between FLI and diabetes risk from various perspectives. This study comprehensively investigated the relationship between FLI and incident diabetes in a large Japanese population. METHODS: This retrospective cohort study included 14,280 participants from Murakami Memorial Hospital in Japan from 2004 to 2015. The independent and dependent variables are FLI and risk of type 2 diabetes mellitus (T2DM), respectively. To examine the link between FLI and incident T2DM, Cox proportional-hazards regression was employed. In addition, we performed a number of sensitivity studies to guarantee the validity of the results. Moreover, we conducted subgroup analyses. RESULTS: After adjusting covariates, the results showed that FLI was positively associated with the risk of T2DM (HR = 1.019, 95%CI: 1.012, 1.025). Additionally, the sensitivity analysis showed how reliable the outcomes were. And a stronger association between FLI and incident T2DM was observed in the regular exercisers (HR = 1.036, 95%CI: 1.019-1.053, P < 0.0001) and the population without ethanol consumption (HR = 1.028, 95%CI: 1.017-1.039, P < 0.0001). Besides, receiver operating characteristic (ROC) curve analysis showed that FLI was better than waist circumference, triglycerides, body mass index, and gamma-glutamyl transferase in predicting incident T2DM. CONCLUSION: FLI is positively associated with incident T2DM.

Transcriptomic characterization and innovative molecular classification of clear cell renal cell carcinoma in the Chinese population.

BACKGROUND: Large-scale initiatives like The Cancer Genome Atlas (TCGA) performed genomics studies on predominantly Caucasian kidney cancer. In this study, we aimed to investigate genomics of Chinese clear cell renal cell carcinoma (ccRCC). METHODS: We performed whole-transcriptomic sequencing on 55 tumor tissues and 11 matched normal tissues from Chinese ccRCC patients. We systematically analyzed the data from our cohort and comprehensively compared with the TCGA ccRCC cohort. RESULTS: It found that PBRM1 mutates with a frequency of 11% in our cohort, much lower than that in TCGA Caucasians (33%). Besides, 31 gene fusions including 5 recurrent ones, that associated with apoptosis, tumor suppression and metastasis were identified. We classified our cohort into three classes by gene expression. Class 1 shows significantly elevated gene expression in the VEGF pathway, while Class 3 has comparably suppressed expression of this pathway. Class 2 is characterized by increased expression of extracellular matrix organization genes and is associated with high-grade tumors. Applying the classification to TCGA ccRCC patients revealed better distinction of tumor prognosis than reported classifications. Class 2 shows worst survival and Class 3 is a rare subtype ccRCC in the TCGA cohort. Furthermore, computational analysis on the immune microenvironment of ccRCC identified immune-active and tolerant tumors with significant increased macrophages and depleted CD4 positive T-cells, thus some patients may benefit from immunotherapies. CONCLUSION: In summary, results presented in this study shed light into distinct genomic expression profiles in Chinese population, modified the stratification patterns by new molecular classification, and gave practical guidelines on clinical treatment of ccRCC patients.

The design, analysis and application of mouse clinical trials in oncology drug development.

BACKGROUND: Mouse clinical trials (MCTs) are becoming wildly used in pre-clinical oncology drug development, but a statistical framework is yet to be developed. In this study, we establish such as framework and provide general guidelines on the design, analysis and application of MCTs. METHODS: We systematically analyzed tumor growth data from a large collection of PDX, CDX and syngeneic mouse tumor models to evaluate multiple efficacy end points, and to introduce statistical methods for modeling MCTs. RESULTS: We established empirical quantitative relationships between mouse number and measurement accuracy for categorical and continuous efficacy endpoints, and showed that more mice are needed to achieve given accuracy for syngeneic models than for PDXs and CDXs. There is considerable disagreement between methods on calling drug responses as objective response. We then introduced linear mixed models (LMMs) to describe MCTs as clustered longitudinal studies, which explicitly model growth and drug response heterogeneities across mouse models and among mice within a mouse model. Case studies were used to demonstrate the advantages of LMMs in discovering biomarkers and exploring drug's mechanisms of action. We introduced additive frailty models to perform survival analysis on MCTs, which more accurately estimate hazard ratios by modeling the clustered mouse population. We performed computational simulations for LMMs and frailty models to generate statistical power curves, and showed that power is close for designs with similar total number of mice. Finally, we showed that MCTs can explain discrepant results in clinical trials. CONCLUSIONS: Methods proposed in this study can make the design and analysis of MCTs more rational, flexible and powerful, make MCTs a better tool in oncology research and drug development.

Shikonin induces necroptosis by reactive oxygen species activation in nasopharyngeal carcinoma cell line CNE-2Z.

Shikonin, a natural small agent, has shown inhibitory effect in many kinds of cells, which increases intracellular reactive oxygen species (ROS) level and causes mitochondrial injury. In this study, shikonin showed good inhibitory effect on nasopharyngeal carcinoma CNE-2Z cells in vivo and vitro. The results presented here revealed that ROS levels increased markly after shikonin treated. The electron microscopy displays the change in ultrastructure of CNE-2Z cells after treatment for shikonin, which indicated that shikonin induced necroptosis. Shikonin-induced cell death was inhibited by a necroptosis inhibitor, necrostatin-1 (Nec-1), while the activity was unaffected by the caspase inhibitor z-VAD-fmk. Furthermore, we have demonstrated that the activation of receptor-interacting kinase (RIP) led to necroptosis. Meanwhile, shikonin also significantly inhibited tumor growth in a CNE-2Z xenograft mouse model. Taken together, shikonin induced CNE-2Z cells death by producing ROS as a necroptosis inducer. It could serve as a new therapeutic agent for treating CNE-2Z cells.

[Effect of oridonin on apoptosis and intracellular reactive oxygen species level in triple-negative breast cancer MDA-MB-231 cells].

Oridonin, which is an ent-kaurene diterpenoid isolated from traditional Chinese medicine Rabdosia rubescens, displays various bioactivities, including anti-inflammation, anti-bacteria and anti-tumor. This study aimed to investigate the effect of oridonin on apoptosis of triple-negative breast cancer MDA-MB-231 cells and its underlying mechanisms. The inhibitory effect of oridonin on proliferation of MDA-MB-231 cells was measured by MTT assay; Apoptosis was analyzed by flow cytometry with PI staining and Annexin V-FITC/PI staining; Intracellular reactive oxygen species (ROS) level was determined by ROS detection kit, and expressions of PARP, Bcl-2, caspase-3 were analyzed by Western blot. The results showed that oridonin exhibited a significant effect in inducing apoptosis of MDA-MB-231 cells, enhancing intracellular ROS level, down-regulating expression of Bcl-2 protein, and promoting cleavage of caspase-3 and its substrate PARP. These results indicated that the apoptosis-inducing effect of oridonin on MDA-MB-231 cells might be correlated with increase of intracellular ROS level, down-regulation of Bcl-2 protein and activation of caspase-3.

NSCLC harboring EGFR exon-20 insertions after the regulatory C-helix of kinase domain responds poorly to known EGFR inhibitors.

Anecdote clinical observations hint that non-small cell lung cancer (NSCLC) with exon-20 insertions might respond poorly to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), contrasting to those with classic mutations. Lack of patient-derived experimental models has been a major hurdle for the discovery of new treatment for the diseases. We established two NSCLC-PDXs harboring two different exon-20 insertions, LU0387-adenocarcinoma (ADC) with a nine-base insertion at 2319 (H773-V774insNPH) and LU3075-squamous cell carcinoma (SCC) with a nine-base insertion at 2316 (P772-H773insDNP). Both insertions immediately follow the regulatory C-helix of the kinase domain. Contrary to the generally good responses to EGFR inhibitors observed in PDXs with classic mutations, both exon-20 insertions are largely resistant to cetuximab and TKIs in vivo, suggesting fundamental difference from the classic EGFR mutations, consistent with the poor response rate to TKI seen in anecdotal clinic reports. It is worth noting that although responses are generally poor, they differ between the two exon-20 mutants depending on the type of TKI. In vitro drug sensitivity assays using established primary cell lines from our two PDXs largely confirmed the in vivo data. Our data from patient-derived experimental models confirmed that exon-20 insertions in domain immediately following the C-helix confer poor response to all known EGFR inhibitors, and suggested that these models can be utilized to facilitate the discovery of new therapies targeting NSCLC harboring exon-20 insertions.

NatD epigenetically activates FOXA2 expression to promote breast cancer progression by facilitating MMP14 expression.

N-α-acetyltransferase D (NatD) mediates N-α-terminal acetylation of histone H4 (Nt-Ac-H4), but its role in breast cancer metastasis remains unknown. Here, we show that depletion of NatD directly represses the expression of FOXA2, and is accompanied by a significant reduction in Nt-Ac-H4 enrichment at the FOXA2 promoter. We show that NatD is commonly upregulated in primary breast cancer tissues, where its expression level correlates with FOXA2 expression, enhanced invasiveness, and poor clinical outcomes. Furthermore, we show that FOXA2 promotes the migration and invasion of breast cancer cells by activating MMP14 expression. MMP14 is also upregulated in breast cancer tissues, where its expression level correlates with FOXA2 expression and poor clinical prognosis. Our study shows that the NatD-FOXA2-MMP14 axis functions as a key signaling pathway to promote the migratory and invasive capabilities of breast cancer cells, suggesting that NatD is a critical epigenetic modulator of cell invasion during breast cancer progression.

An NGS-based assay for accurate detection and quantification of immune gene expression in mouse tumor models.

Tumor microenvironment (TME) is a complex dynamic system with many tumor-interacting components including tumor-infiltrating leukocytes (TILs), cancer associated fibroblasts, blood vessels, and other stromal constituents. It intrinsically affects tumor development and pharmacology of oncology therapeutics, particularly immune-oncology (IO) treatments. Accurate measurement of TME is therefore of great importance for understanding the tumor immunity, identifying IO treatment mechanisms, developing predictive biomarkers, and ultimately, improving the treatment of cancer. Here, we introduce a mouse-IO NGS-based (NGSmIO) assay for accurately detecting and quantifying the mRNA expression of 1080 TME related genes in mouse tumor models. The NGSmIO panel was shown to be superior to the commonly used microarray approach by hosting 300 more relevant genes to better characterize various lineage of immune cells, exhibits improved mRNA and protein expression correlation to flow cytometry, shows stronger correlation with mRNA expression than RNAseq with 10x higher sequencing depth, and demonstrates higher sensitivity in measuring low-expressed genes. We describe two studies; firstly, detecting the pharmacodynamic change of interferon-γ expression levels upon anti-PD-1: anti-CD4 combination treatment in MC38 and Hepa 1-6 tumors; and secondly, benchmarking baseline TILs in 14 syngeneic tumors using transcript level expression of lineage specific genes, which demonstrate effective and robust applications of the NGSmIO panel.

Exploring the Potential Mechanisms of Guanxinshutong Capsules in Treating Pathological Cardiac Hypertrophy based on Network Pharmacology, Computer-Aided Drug Design, and Animal Experiments.

Cardiovascular diseases (CVDs) are significant causes of morbidity and mortality worldwide, and pathological cardiac hypertrophy (PCH) is an essential predictor of many heart diseases. Guanxinshutong capsule (GXST) is a Chinese patent medicine widely used in the clinical treatment of CVD, In our previous research, we identified 111 compounds of GXST. In order to reveal the potential molecular mechanisms by which GXST treats PCH, this study employed network pharmacology methods to screen for the active ingredients of GXST in treating PCH and predicted the potential targets. The results identified 26 active ingredients of GXST and 110 potential targets for PCH. Through a protein-protein interaction (PPI) network, gene ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, we confirmed AKT1, MAPK1, and MAPK3 as the core proteins in GXST treatment of PCH, thus establishing the PI3K/AKT and MAPK signaling pathways as the significant mechanisms of GXST in treating PCH. The results of molecular docking (MD) demonstrate that flavonoid naringenin and diterpenoid tanshinone iia have the highest binding affinity with the core protein. Before performing molecular dynamics simulations (MDSs), the geometric structure of naringenin and tanshinone iia was optimized using density functional theory (DFT) at the B97-3c level, and RESP2 atomic charge calculations were carried out at the B3LYP-D3(BJ)/def2-TZVP level. Further MDS results demonstrated that in the human body environment, the complex of naringenin and tanshinone iii with core proteins exhibited high stability, flexibility, and low binding free energy. Additionally, naringenin and tanshinone iia showed favorable absorption, distribution, metabolism, excretion, and toxicity (ADMET) characteristics and passed the drug similarity (DS) assessment. Ultrasound cardiograms and cardiac morphometric measurements in animal experiments demonstrate that GXST can improve the PCH induced by isoproterenol (ISO). Protein immunoblotting results indicate that GXST increases the expression of P-eNOS and eNOS by activating the PI3K/AKT signaling pathway and the MAPK signaling pathway, further elucidating the mechanism of action of GXST in treating PCH. This study contributes to the elucidation of the key ingredients and molecular mechanisms of GXST in treating PCH.

Narazaciclib, a novel multi-kinase inhibitor with potent activity against CSF1R, FLT3 and CDK6, shows strong anti-AML activity in defined preclinical models.

CSF1R is a receptor tyrosine kinase responsible for the growth/survival/polarization of macrophages and overexpressed in some AML patients. We hypothesized that a novel multi-kinase inhibitor (TKi), narazaciclib (HX301/ON123300), with high potency against CSF1R (IC50 ~ 0.285 nM), would have anti-AML effects. We tested this by confirming HX301's high potency against CSF1R (IC50 ~ 0.285 nM), as well as other kinases, e.g. FLT3 (IC50 of ~ 19.77 nM) and CDK6 (0.53 nM). An in vitro proliferation assay showed that narazaciclib has a high growth inhibitory effect in cell cultures where CSF1R or mutant FLT3-ITD variants that may be proliferation drivers, including primary macrophages (IC50 of 72.5 nM) and a subset of AML lines (IC50 < 1.5 µM). In vivo pharmacology modeling of narazaciclib using five AML xenografts resulted in: inhibition of MV4-11 (FLT3-ITD) subcutaneous tumor growth and complete suppression of AM7577-PDX (FLT3-ITD/CSF1Rmed) systemic growth, likely due to the suppression of FLT3-ITD activity; complete suppression of AM8096-PDX (CSF1Rhi/wild-type FLT3) growth, likely due to the inhibition of CSF1R ("a putative driver"); and nonresponse of both AM5512-PDX and AM7407-PDX (wild-type FLT3/CSF1Rlo). Significant leukemia load reductions in bone marrow, where disease originated, were also achieved in both responders (AM7577/AM8096), implicating that HX301 might be a potentially more effective therapy than those only affecting peripheral leukemic cells. Altogether, narazaciclib can potentially be a candidate treatment for a subset of AML with CSF1Rhi and/or mutant FLT3-ITD variants, particularly second generation FLT3 inhibitor resistant variants.

Overcoming erlotinib resistance with tailored treatment regimen in patient-derived xenografts from naïve Asian NSCLC patients.

Overall benefits of EGFR-TKIs are limited because these treatments are largely only for adenocarcinoma (ADC) with EGFR activating mutation. The treatments also usually lead to development of resistances. We have established a panel of patient-derived xenografts (PDXs) from treatment naïve Asian NSCLC patients, including those containing "classic" EGFR activating mutations. Some of these EGFR-mutated PDXs do not respond to erlotinib: LU1868 containing L858R/T790M mutations, and LU0858 having L858R mutation as well as c-MET gene amplification, both squamous cell carcinoma (SCC). Treatment of LU0858 with crizotinib, a small molecule inhibitor for ALK and c-MET, inhibited tumor growth and c-MET activity. Combination of erlotinib and crizotinib caused complete response, indicating the activation of both EGFR and c-MET promote its growth/survival. LU2503 and LU1901, both with wild-type EGFR and c-MET gene amplification, showed complete response to crizotinib alone, suggesting that c-MET gene amplification, not EGFR signaling, is the main oncogenic driver. Interestingly, LU1868 with the EGFR L858R/T790M, but without c-met amplification, had a complete response to cetuximab. Our data offer novel practical approaches to overcome the two most common resistances to EGFR-TKIs seen in the clinic using marketed target therapies.

HX009, a novel BsAb dual targeting PD1 x CD47, demonstrates potent anti-lymphoma activity in preclinical models.

Both PD1/PD-L1 and CD47 blockades have demonstrated limited activity in most subtypes of NHL save NK/T-cell lymphoma. The hemotoxicity with anti-CD47 agents in the clinic has been speculated to account for their limitations. Herein we describe a first-in-class and rationally designed bispecific antibody (BsAb), HX009, targeting PD1 and CD47 but with weakened CD47 binding, which selectively hones the BsAb for tumor microenvironment through PD1 interaction, potentially reducing toxicity. In vitro characterization confirmed: (1) Both receptor binding/ligand blockade, with lowered CD47 affinity; (2) functional PD1/CD47 blockades by reporter assays; (3) T-cell activation in Staphylococcal-enterotoxin-B-pretreated PBMC and mixed-lymphocyte-reaction. In vivo modeling demonstrated antitumor activity in Raji-B and Karpass-229-T xenograft lymphomas. In the humanized mouse syngeneic A20 B-lymphoma (huCD47-A20) HuGEMM model, which has quadruple knocked-in hPD1xhPD-L1xhCD47xhSIRPα genes and an intact autologous immune-system, a contribution of effect is demonstrated for each targeted biologic (HX008 targeting PD1 and SIRPα-Fc targeting CD47), which is clearly augmented by the dual targeting with HX009. Lastly, the expression of the immune-checkpoints PD-L1/L2 and CD47 seemed co-regulated among a panel of lymphoma-derived-xenografts, where HX009 maybe more effective in those with upregulated CD47. Our data warrants HX009's further clinical development for treating NHLs.

The SMARCA4R1157W mutation facilitates chromatin remodeling and confers PRMT1/SMARCA4 inhibitors sensitivity in colorectal cancer.

Genomic studies have demonstrated a high frequency of genetic alterations in components of the SWI/SNF complex including the core subunit SMARCA4. However, the mechanisms of tumorigenesis driven by SMARCA4 mutations, particularly in colorectal cancer (CRC), remain largely unknown. In this study, we identified a specific, hotspot mutation in SMARCA4 (c. 3721C>T) which results in a conversion from arginine to tryptophan at residue 1157 (R1157W) in human CRC tissues associated with higher-grade tumors and controls CRC progression. Mechanistically, we found that the SMARCA4R1157W mutation facilitated its recruitment to PRMT1-mediated H4R3me2a (asymmetric dimethylation of Arg 3 in histone H4) and enhanced the ATPase activity of SWI/SNF complex to remodel chromatin in CRC cells. We further showed that the SMARCA4R1157W mutant reinforced the transcriptional expression of EGFR and TNS4 to promote the proliferation of CRC cells and patient-derived tumor organoids. Importantly, we demonstrated that SMARCA4R1157W CRC cells and mutant cell-derived xenografts were more sensitive to the combined inhibition of PRMT1 and SMARCA4 which act synergistically to suppress cell proliferation. Together, our findings show that SMARCA4-R1157W is a critical activating mutation, which accelerates CRC progression through facilitating chromatin recruitment and remodeling. Our results suggest a potential precision therapeutic strategy for the treatment of CRC patients carrying the SMARCA4R1157W mutation.

A living biobank of matched pairs of patient-derived xenografts and organoids for cancer pharmacology.

Patient-derived tumor xenograft (PDX)/organoid (PDO), driven by cancer stem cells (CSC), are considered the most predictive models for translational oncology. Large PDX collections reflective of patient populations have been created and used extensively to test various investigational therapies, including population-trials as surrogate subjects in vivo. PDOs are recognized as in vitro surrogates for patients amenable for high-throughput screening (HTS). We have built a biobank of carcinoma PDX-derived organoids (PDXOs) by converting an existing PDX library and confirmed high degree of similarities between PDXOs and parental PDXs in genomics, histopathology and pharmacology, suggesting "biological equivalence or interchangeability" between the two. Here we demonstrate the applications of PDXO biobank for HTS "matrix" screening for both lead compounds and indications, immune cell co-cultures for immune-therapies and engineering enables in vitro/in vivo imaging. This large biobank of >550 matched pairs of PDXs/PDXOs across different cancers could become powerful tools for the future cancer drug discovery.

Pharmacological characterization of chemically synthesized monomeric phi29 pRNA nanoparticles for systemic delivery.

Previous studies have shown that the packaging RNA (pRNA) of bacteriophage phi29 DNA packaging motor folds into a compact structure, constituting a RNA nanoparticle that can be modularized with functional groups as a nanodelivery system. pRNA nanoparticles can also be self-assembled by the bipartite approach without altering folding property. The present study demonstrated that 2'-F-modified pRNA nanoparticles were readily manufactured through this scalable bipartite strategy, featuring total chemical synthesis and permitting diverse functional modularizations. The RNA nanoparticles were chemically and metabolically stable and demonstrated a favorable pharmacokinetic (PK) profile in mice (half-life (T(1/2)): 5-10 hours, clearance (Cl): <0.13 l/kg/hour, volume of distribution (V(d)): 1.2 l/kg). It did not induce an interferon (IFN) response nor did it induce cytokine production in mice. Repeat intravenous administrations in mice up to 30 mg/kg did not result in any toxicity. Fluorescent folate-pRNA nanoparticles efficiently and specifically bound and internalized to folate receptor (FR)-bearing cancer cells in vitro. It also specifically and dose-dependently targeted to FR(+) xenograft tumor in mice with minimal accumulation in normal tissues. This first comprehensive pharmacological study suggests that the pRNA nanoparticle had all the preferred pharmacological features to serve as an efficient nanodelivery platform for broad medical applications.

Can collaborative innovation constrain ecological footprint? Empirical evidence from Guangdong-Hong Kong-Macao Greater Bay Area, China.

Collaborative innovation can promote scientific productivity and the development of clean technology and thus has a great potential in constraining the ecological footprint. However, current studies on the impact of collaborative innovation on ecological footprint are insufficient, and results remain controversial. To better understand these impacts, this paper took Guangdong-Hong Kong-Macao Greater Bay Area of China as a case, estimated the ecological footprint at the municipal level from 2008 to 2018, measured collaborative innovation both from four dimensions and from a composite approach, then applied threshold regression models to compare the impact of collaborative innovation on the ecological footprint across different economic intervals. The findings showed that: the ecological footprint of the Greater Bay Area displayed an overall upward trend with prominent spatial heterogeneity. The impact of collaborative innovation on the ecological footprint presented a double-threshold effect when examined with different indicators. Among which, the flow of scientific personnel and capital boosted the ecological footprint, which intensified with economic development, while collaboration in technology exerted significant inhibitory effects on ecological footprint, and the influence of inter-city knowledge collaboration was limited. Overall, collaborative innovation inhibited ecological footprint when measured by a composite index. This might inspire policymakers to adopt sustainable strategies depending on the type of collaborative innovation and the economic status of the city to constrain growth of the ecological footprint, thus minimizing the pressures of human activities on the environment and moving towards a more carbon neutral society.

[Corrigendum] 3­Bromopyruvate sensitizes human breast cancer cells to TRAIL­induced apoptosis via the phosphorylated AMPK­mediated upregulation of DR5.

Following the publication of this article, an interested reader drew to the authors' attention that the western blotting data shown in Fig. 3 on. p. 2439 contained apparent anomalies; first, the protein bands shown to represent the CHOP and p­AMPK experiments in Fig. 3A were strikingly similar. Secondly, the same data bands were inadvertently included in the figure to represent the GRP78 and Bax experiments for the MCF­7 group. The authors have re­examined their original data and realized that this figure was assembled incorrectly (the CHOP and GRP78 data were inadvertently duplicated in the figure). The corrected version of Fig. 3, showing the correct data for the p­AMPK and Bax experiments for the MCF­7 group in Fig. 3A, is shown on the next page. The authors sincerely apologize for the error that was introduced during the preparation of this figure, thank the Editor of Oncology Reports for granting them the opportunity to publish a Corrigendum, and are grateful to the reader for alerting them to this issue. The authors also regret any inconvenience that this mistake may have caused. [the original article was published in Oncology Reports 40: 2435­2444, 2018; DOI: 10.3892/or.2018.6644].

Tumor Purity in Preclinical Mouse Tumor Models.

Tumor biology is determined not only by immortal cancer cells but also by the tumor microenvironment consisting of noncancerous cells and extracellular matrix, together they dictate the pathogenesis and response to treatments. Tumor purity is the proportion of cancer cells in a tumor. It is a fundamental property of cancer and is associated with many clinical features and outcomes. Here we report the first systematic study of tumor purity in patient-derived xenograft (PDX) and syngeneic tumor models using next-generation sequencing data from >9,000 tumors. We found that tumor purity in PDX models is cancer specific and mimics patient tumors, with variation in stromal content and immune infiltration influenced by immune systems of host mice. After the initial engraftment, human stroma in a PDX tumor is quickly replaced by mouse stroma, and tumor purity then stays stable in subsequent transplantations and increases only slightly by passage. Similarly, in syngeneic mouse cancer cell line models, tumor purity also turns out to be an intrinsic property with model and cancer specificities. Computational and pathology analysis confirmed the impact on tumor purity by the diverse stromal and immune profiles. Our study deepens the understanding of mouse tumor models, which will enable their better and novel uses in developing cancer therapeutics, especially ones targeting tumor microenvironment. Significance: PDX models are an ideal experimental system to study tumor purity because of its distinct separation of human tumor cells and mouse stromal and immune cells. This study provides a comprehensive view of tumor purity in 27 cancers in PDX models. It also investigates tumor purity in 19 syngeneic models based on unambiguously identified somatic mutations. It will facilitate tumor microenvironment research and drug development in mouse tumor models.